Plot Imouto de Ikou! OVA Subtitle Indonesia

When her
family is overthrown in a coup d'état, Princess Mayuka is sent to Earth
to recharge the Ultimate Weapon. After studying the mating behaviors of
Earthlings, she decides to enlist the help of one of her research
subjects, college student Yoshizumi, but crash-lands on his roof. Taken
hostage and shot with her own gun by Yoshizumi, she is brainwashed into
thinking she is his younger sister.